It was narrated from 'Urwah bin Mughirah bin Shu'bah from his father Mughirah bin Shu'bah, that:
The Messenger of Allah went out to relieve himself, and Mughirah followed him with a vessel of water. When he finished relieving himself, he performed ablution and wiped over his leather socks. (IT)
English reference (IT): Vol. 1, Book 1, Hadith 545 (IT)
Arabic reference (IT): Book 1, Hadith 588 (IT)